The properties of many dental materials are enhanced when preheated just prior to clinical usage. Examples of such dental materials include etching agents, bleaching compositions, dental cements, impression materials and more particularly photocurable dental restorative materials. It is typical to prepackage a unit dosage of the dental material in a cartridge, which shall hereafter be referred to as a compule. A dispensing syringe or gun is commonly used in the dental profession to discharge the contents of dental material from a compule directly into the patient's mouth during clinical usage.
Applicant teaches in U.S. Pat. Nos. 6,236,020 and 6,320,162, each disclosure of which is herein incorporated by reference, a method and apparatus by which a compule of dental material can be heated prior to insertion into a dispensing syringe or gun. However, in the preparation of a dental restoration a compule may be dispensed several times in sequence so as to form successive layers. In fact, the American Dental Association and all manufacturers of dental light cured materials recommend using a layering technique involving curing of filling material in successive 2 mm maximum layers as the best way to achieve the most polymerization and hence the best physical properties. When a layering technique is used, removing the compule from the standard dispenser to reheat it before placing it back into the dispenser is cumbersome and time consuming. This procedure may, in fact, have to be repeated three or four times during the course of any given restoration so that each layer is preheated to a uniform temperature and is accordingly a drawback in the use of the method and apparatus of the aforementioned patents.
A dispensing syringe or gun which incorporates a heating assembly within the dispenser itself is taught by Applicant in U.S. Pat. No. 6,312,254. Although this arrangement will overcome the disadvantages of removing and reinserting the compule in the dispenser each time the compule is partially dispensed this is a substantially more complex and expensive dispensing syringe than the standard dispenser, which is in common usage.
The present invention permits a conventional dispenser with any known prepackaged compule of dental material to be heated without removal from the dispenser.